Claim CI101:

Complexity indicates intelligent design.

Response:

This is a quintessential argument from
incredulity. Complexity
usually means something is hard to understand. But the fact that one
cannot understand how something came to be does not indicate that one
may conclude it was designed. On the contrary, lack of understanding
indicates that we must not conclude design or anything else.

In the sort of design that we know about, simplicity is a design goal.
Complexity arises to some extent through carelessness or necessity, but
engineers work to make things as simple as possible. This is very
different from what we see in life.

Complexity arises from natural causes: for example, in weather patterns
and cave formations.